The field of electronic vehicle tracking for tolling and other purposes has seen many iterations over the years. These include the use of vehicle-based backscatter transponders detected and communicated with by roadside equipment, active transponders detected and communicated with by roadside equipment, hybrid transponders having both active and backscatter functions; and video monitoring of vehicle license plate and other placards. Cellular telephones have also been described for use in tolling systems, alone or in combination with the aforementioned types of transponders.
One problem in tolling applications that exists regardless of the technology used is determination of the roadway lane in which the vehicle is travelling. This is critical for several reasons. Firstly, because open road tolling systems frequently employ multiple transponder detection antennas and systems to cover multiple lanes of travel, it is necessary to accurately determine lane of travel so that vehicles are not recorded more than once per crossing and so that ancillary lane-based detection equipment such as light curtains, treadles and license plate cameras are coordinated with the correct lane of travel of the detected vehicle. Secondly, various tolling and roadway traffic management operations provide incentives and/or restrictions for vehicles of different types and occupancy levels, these include the ability to travel in restricted lanes, thus it is necessary to determine if a vehicle is travelling in the required or allowed lane.
Another use of vehicle-based transponder technology is providing secure access to limited access facilities. While tolling agencies may register tolling transponders based on vehicle identification data such as license plates, such a system may be impractical for issuing devices to access a facility because, for instance, the user may legitimately use different vehicles. In these cases issuing access devices to an end user may be made on a different basis than vehicle identification. The use of smart phones as transponders in to provide access to gated facilities provides opportunities to arrange access that is not limited to a single user vehicle and that uses a device the user already has and is not likely leave in an unused vehicle.